Hi! This is Rafa Monteiro, from Montpellier, France. This is an assignment for lesson for week 6 of “Introduction To Music Production” at Coursera.org. Today, I would like to talk to you about synthesizers: what are they, and how can they be properly used.
The story of those machines dates back to the early 20th century, in which the advances of electronics technology enabled us to understand and convert sound into an analog electrical signal. That enabled us to build radio stations, telephones, microphones and so forth.
But, what if instead of convert a natural sound into an electric signal for recording purposes, we could build our own sound from scratch? By reversing the way in which technology was being used – that is, to build (synthesize) sound from a given electric signal instead of build a signal from (analyzed) sound – we could create completely different sounds that were impossible to make with traditional instruments.
That’s the idea behind the synthesizer. It’s a machine to build sound from scratch, with many buttons and controls that enables us to modify it’s parameters.
Synthesizers used to be heavy and complex machines, that got smaller and cheaper over time. Nowadays, most synths are computer programs meant to be controlled by some device (usually a MIDI one). But many of that old, hardware synths are still being used in concerts and shows all around the world, due to their awesome sound.
They all have many buttons, that might scare at first sight. Their functioning, however, is the same for all devices and plugins: every synth work with at least one Oscillator, one Filter, one Amplifier, one Envelope, and one LFO modules. Bigger, heavier (in terms of weight or CPU usage) and more expensive one can have a lot of modules, but all of them will fit one of these categories.
- Oscillator: This module is responsible to create the oscillation in the voltage, thus creating the sound. They all have a control that allow us to choose the shape waveform generated (usually sine wave, saw tooth, triangle, square and noise), with a different timbre for each waveform created. Some oscillators also have extra modules, that allows us to change the timbre by additive or subtractive synthesis of two or more different waveforms generated.
- Filter: This module is an equalizer build in the synth, that allows us to control the generated timbre by boosting or cutting ranges of frequencies. The most simple filter available (and the most commonly used) is the low pass filter, but many synthesizers have EQs with more filtering options and parameters – high pass, band pass, notch filters and etc.
- Envelope: This module is also called ADSR envelope and allow us to work in the periodic response of the generated sound when activated (or deactivated) by a controller key. Just like musical instruments have their sound modified over time, synthesizers can create and emulate that time-based response with this module. ADSR means: A = Attack, which is a value that determine the speed which the sound reaches it’s full amplitude. Higher attack means that the note will take more time to go from zero to full value. D = Decay, which is a value that determine how fast the note starts being sustained if the key controller remains pressed. S = Sustain, which determines the level of the sustained note whole the key controlled is pressed. Zero means no sustain, with full meaning full note. R = Release, which means how fast the sound returns to zero once the key controller is released. Bigger release time means a more lasting sound for the released note.
- LFO: This module is a Low Frequency Oscilator, that generates a low frequency (usually below 20 Hz, out of our audible range) that can be used to control other modules. The sound of the vibrato or tremolo is made through the LFO.
- Amplifier: This module works as a preamp, by boosting (and possibly distorting, too) the generated signal. It’s usually the last module before sending the signal to external devices or speakers, that will raise the gain of the final synthesized signal.
Older, simpler and cheaper synthesizers usually have their modules hardwired to work with an specific signal flow. However, there are more complex synths (usually plugins) that allows us to change the order in which those modules affect the signal, or even how they are controlled. It’s possible, for example, to use an LFO to control an envelope filter, or control the amplification stage through an envelope, for example. Another would be using more than a single filter to create different EQs – and we are not even talking of synths with built in compressors, delays or distortion modules.
Another important point is that a synth requires a controller in order to work as a musical instrument. A hardware synth will usually come with a built in keyboard, but many won’t (specially the plugins) and require a controller in order to work properly. It’s pretty much like a video game, that needs an interface or controller to allow you to play.
Synthesizers allow us go beyond the limits of the traditional instruments. In this beautiful piece of music, for example, Brad Mehldau plays a synth with an Hammond organ to build different layers and textures of sound
Synths are the pillars of the electronic music and a very important tool in Progressive Rock, Metal, Pop, Hip Hop and Fusion. Virtually any music style that is not solely played by acoustic instruments eventually end up using synths in some fashion – and even classical pieces sometimes require synths. Chances are that you will end up using them a lot, and it’s very important to understand their functioning in order to extract the perfect sound you are after.